A known molten metal furnace comprises a large generally rectangular metal box internally lined with high temperature insulating board which shields the steel furnace walls from degradation by molten metal in the furnace. Sloped, forwardly and upwardly facing, doors are closed to cover an opening in the front portion of the furnace top wall and extending into the top portion of the furnace front wall. The sloped doors are typically hinged along their rear edges to the central portion of the furnace top. The doors are normally closed during ongoing heating of metal in the furnace to render such metal molten. During operation, the furnace contains a pool of molten metal heated by conventional means, the top of the metal bath being below the bottom edge of the door opening. Furnaces of the above-described type are for example used for melting scrap pieces of metal, such as scrap aluminum or zinc pieces.
Molten metal is removed periodically from the furnace by conventional means which do not require discussion here. It is thus necessary to periodically add metal to be melted to the furnace. It has been common in the past to load a furnace of this type by opening the doors and dumping a quantity of pieces of scrap directly at the furnace through the door opening, from a container carried by a forklift truck.
However, occasionally, when care is not taken, this loading method may cause problems. For example pockets of cutting oil or water may be present in the scrap. Further, it has been known to add several containers of scrap to a furnace, one immediately after the other, and to tamp down the scrap with the forks of the forklift truck. A pocket of liquid which happens to be left in the scrap from the first container may thus be forced down into the existing molten metal bath in the furnace and be almost instantaneously vaporized and/or ignited and expand explosively. Thus, a series of errors in batch loading of scrap into the furnace through the open doors could possibly result in an explosion.
Prior to the present invention, the present inventor designed and built a loading unit to avoid such batch loading of scrap into a furnace through the doors. Such loading unit aligned a linear vibrating conveyor with a hole in the side of the furnace, above the molten metal level therein. An air curtain directed into the output end of the conveyor helps protect it from damage by hot gases escaping from the furnace through the hole in the side of the furnace. The vibrating conveyor used was a Model Furnace Feeder made by Prab, located in Kalamazoo, Mich. However, the scrap metal placed on the conveyor frequently is of irregular shape, for example flashing from trim presses or sprues and runners from die casting machines. Irregular scrap of this kind tends to become tangled up in a mass on the conveyor, occasionally jamming the conveyor and thereby stopping the feed of scrap material into the furnace. Such stoppages interfered with continuous feeding of scrap to the furnace and required manual attention to restore normal feeding.
Accordingly, the objects and purposes of the present invention are met by providing a scrap loader for a molten metal furnace, which is intended to avoid the above-discussed problems of scrap loading, which provides for positive feeding at a controlled continuous rate of metal scrap of even irregular readily tangled shapes, which is compact and readily mountable beside existing furnaces, and which can be constructed from readily available parts and materials at relatively modest cost.
Other objects and purposes of this invention will be apparent to persons acquainted with apparatus of this general type upon reading the following description and viewing the accompanying drawings.
The objects and purpose of this invention are met by providing a scrap loader for a molten metal furnace, comprising a chamber having an inlet port for receiving scrap metal and an outlet port through which metal scrap is to be fed into the furnace. A ram assembly comprises a ram pivotal along a wall of the chamber past the inlet port and toward the outlet port and means actuable for pivotally actuating the ram to drive the metal scrap along the wall and through the outlet port into the furnace.